Party telephone signaling arrangement



Aug. 30, 1932. w. H. EDWARDS 1,374,472

PARTY TELEPHONE SIGNALING ARRANGEMENT Filed April 10. 1931 INVENTOR Al IORNEY Patented Aug. 30, 1932 Iran :srrareis PATIENT OFFIOE WILLIAM H. EDWARDS, OF GREAT 'NEGK, NEW YORK, ASSIGNOR TO AIMEE-EGAN TELE- EHONE.AND .TEIEEGRAPH COMPANY, A CORPORATION OF NEWTYORK IPARTY'TELEPHONE SIGNALING ARRANGEMENT Application filed April 10, 1931. SerialNo. 529,255.

This invention relatesto telephone systems and-more particularly .to signaling arrangements-forv use on. party linesin such systems.

The ringing'or signaling arrangements of the inventionare particularly applicable to the type of telephonelines known as divided ringing magneto party lines, such for example as two-party selective lines, four-party semi-selective lines, and ten-party lines with five stations on either side of the. line signaled by five difierent codes. One oftheprimary objects of the ringingarrangements ofthe invention is to provide for improvedringing margins, or in other words. greater sensitivity, in the rmgmg apparatusat the subscribers stations while at the-same time preventing false operation of the ringers on cross ringing currents. The arrangements of the invention also make it possible .to extend the maximum subscribers loop circuits. Other objects and features of the invention will appear more fully from the detailed description ofv the invention hereinafter given.

In party telephone lines of the type to which the invention is particularly applicable one of the chief causes of narrow ringing margins or limitations in maximum subscribers loops at party line stations thereon, which are rung over one side of the line to ground is the necessity for-decreasing the sensitivity of the station ringers to avoid their false operation on cross ringing currents. This cross ringing or false operation is liable to occur when a subscriber takes his receiver from the hook during the period when ringing current is applied to the line. The subscribers set is bridged across the line and, when the receiver is removed from the hook, provides a path for the ringing current applied to one side of the line over the other side of the line to ground at the office. If the loop is comparatively long, the current flowing through the resistance of the line will cause a diiference in potential across the ringers on the side of the line which it is not intended to ring. To prevent false operation of these ringers on this drop in potential, it has heretofore been necessary to increase their biasing spring tensions Which reduces their sensitivity to regular ringing current. This is avoided in the arrangements of the invention by insertingin the talking conductors of the subscribers set a device, such as a condenser, having a relatively high impedance to the ringing currents and a low impcdanceto talking currents. In th s manner the ringing current which might flow over the return side of the line to ground is reduced and the difference in potential across the ringers on the return side of the line is reduced. This practically eliminates the need for biasing at a central oflice to'ringing apparatus designated 1, whereby'ringing current may be applied either to the tip or ring side of the line. This ringing current may be either alternating-current, pulsating current or superimposed ringing current, and the signals will be sent out in different codes. Connected to the party line 'L are shown two subscriber stations,2 and 3. Station 2 comprises a telephonereceiver 5, a transmitter 6, a switch hook 7, the usual induction coil 8, ringing apparatus 9, and ringing responsive apparatus R which is connected to ground and the ring side of the line. Station 8, comprises a telephone receiver 10 and transmitter 11, a switch hook 12, induction coil 13, ringing apparatus 14 and ringing responsive apparatus R connected to ground and the tip side of the line. Connected to the tip side of the line are shown the ringing responsive devices R R R and R These ringing responsive devices are similar to the ringer R and would beassociated with separate subscriber sets not shown. Associated with the ring side sive device R and would be connected with different subscriber sets not shown.

If it should be desired to ring one of the subscriber sets, such for example as the one including the ringing responsive device R ringin current would be applied at the central 0 cc to the tip side of the line by the ringer 1 and a code signal would be sent over the tip side of the line and through .the responsive device R to ground. If while rin ing current was thus being applied to the line one of the subscribers, such for example as the subscriber at station 3, should remove his receiver from the switch hook, a circuit would be closed through the subscribers set and over :the ring side of the line to ground at the ringer 1 in the central oflice. If the line L was comparatively short, a short circuit would exist around the ringing responsive devices R to R and they would not be affected. However, if the line L Was'comparatively long, the resistance of the line would cause a difference in potential to exist across these ringers connected to the ring side ofthe line. Heretofore, to prevent false operation of these ringerson this drop in potential, it has been necessary to increase biasing spring tensions which reduce, their sensitivity to regular ringing current. Accordingly, in the arrangement of this invention there is provided in each subscribers set inseries with the induction coil and receiver thereof condensers, such as 15 and 16. These condensers have a relatively high impedence to ringing current, and a relatively low impedance to talking current. This raises the impedance of the subscribers set to ringing current compared to sets without this condenser when the receiver is removed from the hook during the application of rin ing current to the line, so that the current 0W- ing over the return side of the line to ground is reduced and the difference in potential across the ringers onthe return side of theline is lowered. This practically eliminates the need for biasing the ringers against cross ringing and permits the ringers to be given a very sensitive adjustment and the maximum length of the loop to be increased.

While the invention has been discussed as embodied in certain specific forms that are I desirable, it is understood that it is applica- V ble to other types of lines and is capable of embodiment in many and other widely varied forms withoutdeparting from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. A party telephone line having a plurality of signal responsive devices connected to each side of said line and ground, means for applying signallng current to said llne,

' a subscribers telephone setbridged across said line, and means operatively included in said subscribers set when the receiver thereof is removed from the hook having a relatively high impedance to said signaling current and a low impedance to currents used for talking'purposes.

2. In a telephone system a magneto divided ringing party line, a subscribers set bridged across said line, and means included in said subscribers set when the receiver of said subscribers set is removed from the hook thereof for preventing cross ringing difficulties during the application of signaling current to theline, said means comprising a device in the circuit of said subscribers set having a relatively high impedance for signaling currents and a low impedance for currents used for talking purposes.

3. In a telephone system a magneto divided ringing party line,'a plurality of signal responsive devices connected to each side of .said line and ground, a subscribers set bridged across said line, and a condenser operatively connected in series with the receiver and induction coil of said, subscribers set when the receiver thereof is removed from the hook having a relatively high impedance to signaling currents applied to said line and a low impedance to currents used for talking purposes.

4 In a telephone system a magneto divided ringing party line, a plurality of subscribers sets bridged across said line, each 

